HDFC Bank — Cashback not received

Address: hdfc talwandi kota branch

I bought lenovo desktop using hdfc credit card on 16/10/20 and was delievered on 19/10/20 but as per sale condition cashback to be receieved within 30 days. when will i receieve my cashback. sale condition and bill are attached with the complaint and additional details can be checked with my credit card statement.
contact no.[protected].